If you want a bit of variety while streaming or as a bonus incentive for something, etc., you can play wearing the angel costume from the demo by simply copying over the file from the demo ISO (c002.ptm) and renaming it as c001. You'll have to extract/replace the file in Dolphin or GCRebuilder/GCFT. Here's the demo outfit file.

https://mega.nz/folder/JxdDWZjZ#snPaeogNYJt2vAC8gVcVLA In-game screenshot:

I've done a similar method, but instead of model replacement, I've replaced the texture for Tara's outfit with the demo outfit, then enabled custom textures in Dolphin.